There are some types of image forming apparatuses for continuously printing both sides of a recording medium, including opposing printing heads with a recording medium conveyance path interposed therebetween.
Such types of image forming apparatuses generally include thermal heads disposed in the vicinity of upstream and downstream in a recording medium conveyance direction. The thermal heads are disposed opposite to a platen with the recording medium conveyance path interposed therebetween. The recording medium is conveyed by rotation of the platen. The conveyance of the recording medium requires rotating the platen with the thermal heads pressurized to the platen.
However, when an image is to be formed near a tailing end of the recording medium, if the thermal head located upstream in the recording medium conveyance direction continues to be pressurized to the platen even when the tailing end of the recording medium is escaped from the thermal head, then the thermal head may be worn out by contact with the platen.
In this regard, there has been proposed a technique to adjust a pressurizing force of a head using a cam.
However, two sets of thermal heads and platens require a more complicated control.
Accordingly, there is a need of an image forming apparatus and a head pressurizing force adjusting method, which can change a pressurizing force of thermal heads depending on a position of a tailing end of a recording medium.